The present invention relates to an adjustable seat in general, and more particularly to an adjustable seat to be mounted in a motor vehicle or the like.
SUCH ADJUSTABLE SEATS ARE ALREADY KNOWN AND HAVE GAINED WIDESPREAD ACCEPTANCE, PARTICULARLY IN THE AUTOMOBILE INDUSTRY. Such seats may be of any of a variety of constructions, among them such in which the seat element is supported, at each of its lateral regions, on a mounting arrangement which consists of a front guide track associated with the front region of the seat element, and on a separate and distinct rear guide track the direction of which differs from that of the front guide track and which is associated with the rear region of the seat element.
An adjustable seat of this construction is already known, for instance, from the German Pat. No. 766,073 in which, at each of the lateral regions of the seat element, the front guide track slopes upwardly in the forward direction of the seat element to a comparably small extent, while the rear guide track has a steeper slope in the same vertical plane. The seat element is guided in the front guide tracks by means of rollers which are secured against lifting by means of a rail. On the other hand, the rear guide tracks are constructed as suspension rails, and the above-discussed securing of the rollers is dispensed with at the rear guide tracks.
The roller support of the front and of the rear regions of the seat element requires, for a sufficiently long support base, a substantial length of the guide track arrangement because, were it otherwise, the range of adjustment would be disadvantageously and severely limited.
On the other hand, it is also already known from the U.S. Pat. No. 2,953,190 to provide a seat for use in vehicles which is longitudinally adjustable. In this adjustable seat, there is provided, at each of the lateral regions of the seat element, a guide track which is curved over the length thereof and which is anchored to the floor of the motor vehicle, the seat element being guided on such guide tracks by means of support members. A longitudinally oriented toothed rack is rigidly connected to the seat element next to the support members, and a pinion driven by an electric motor meshes with such a toothed rack. The seat element is held in the respectively selected longitudinal position thereof as a result of the self-locking feature of the drive or transmission, in particular of a worm transmission interposed between the motor and the pinion. Even in such seats in which a longitudinally extending guide track is arranged at each lateral region of the seat element and in which the rear as well as the front region of the seat element is supported, the same problem as explained above is encountered, that is, given a certain length of the guide track, the range of adjustment of the seat element is rather small or, for a predetermined adjustment range, the length of the mounting arrangement is rather great.
There is also already known from the U.S. Pat. No. 3,079,118, an adjustable seat to be arranged in a motor vehicle in which the seat element is shiftable in a longitudinally extending guiding arrangement by means of an electromotor and a transmission which includes a crank and a connecting rod. The structural arrangement which constitutes the guiding arrangement is supported, at its both end regions, by pivotable levers which are selectably driven by means of an electromotor. As a result of this, the longitudinal position, the height, and the inclination of the seat element can be adjusted to the requirements or wishes of the user of the adjustable seat. A sole electromotor is provided in this arrangement which can be switched to drive the various transmissions by means of electromagnetically energizable couplings. Seats of this kind are expensive and have relatively huge weights. Also, they require a substantial structural length as compared to the achievable range of adjustment. In addition thereto, there exists the danger of operational difficulties or malfunction. Furthermore, the adjustment presupposes a technical understanding in order for the user of the adjustable seat to be able to exactly and quickly achieve the desired position of the seat.